The present invention relates to a Stirling refrigerating machine.
FIG. 3 is a sectional view schematically showing an example of a conventional Stirling refrigerating machine. First, the structure of this conventional Stirling refrigerating machine will be described with reference to FIG. 3. A cylinder 1 has a cylindrical space formed inside it, and, in this space, a displacer 2 and a piston 3 are arranged so as to form a compression space 6 and an expansion space 7, between which a regenerator 8 is provided to form a closed circuit. This closed circuit has its working space filled with working gas such as helium, and the piston 3 is made to reciprocate along its axis (in the direction marked F) by an external power source such as a linear motor (not shown) or the like. The reciprocating movement of the piston 3 causes periodic pressure variations in the working gas sealed in the working space, and causes the displacer 2 to reciprocate along its axis.
A displacer rod 4 penetrating the piston 3 is, at one end, fixed to the displacer 2 and, at the other end, connected to a spring 5. The displacer 2 reciprocates along its axis inside the cylinder 1 with the same period as but with a different phase from the piston 3. As the displacer 2 and the piston 3 move with an appropriate phase difference kept between them, the working gas sealed in the working space forms a thermodynamic cycle well-known as the reversed Stirling cycle, and produces cold mainly in the expansion space 7.
The regenerator 8 is a matrix of fine wire or a ring-shaped gap formed by wounding foil. As the working gas moves from the compression space 6 to the expansion space 7, the regenerator 8 receives heat from the working gas and stores the heat. As the working gas returns from the expansion space 7 to the compression space 6, the regenerator 8 returns the heat stored in it to the working gas. Thus, the regenerator 8 serves to store heat.
Reference numeral 9 represents a high-temperature-side heat exchanger, through which part of the heat generated when the working gas is compressed in the compression space is rejected to outside. Reference numeral 10 represents a low-temperature-side heat exchanger, through which heat is taken in from outside when the working gas expands in the expansion space 7.
Now, how this structure works will be described briefly below. When compressed by the piston 3, the working gas in the compression space 6 moves, as indicated by the solid-line arrow A in the figure, through the regenerator 8 to the expansion space 7. Meanwhile, the heat of the working gas is rejected through the high-temperature-side heat exchanger 9 to outside, and thus the working gas is precooled as the result of its heat being stored in the regenerator 8. When most of the working gas has flowed into the expansion space 7, it starts expanding, and produces cold in the expansion space 7.
Next, the working gas moves, as indicated by the broken-line arrow B in the figure, through the regenerator 8 back to the compression space 6. Meanwhile, the working gas takes in heat from outside through the low-temperature-side heat exchanger 10, and collects the heat stored in the regenerator 8 half a cycle ago before entering the compression space 6. When most of the working gas has returned to the compression space 6, it starts being compressed again, and thus proceeds to the next cycle. This cycle is repeated continuously, and cryogenic cold is thereby produced.
In this structure, the regenerator 8 is realized, for example, with film of polyester or the like wound in a cylindrical shape. However, here, variations are inevitable in the gaps between different layers of the film so wound, and therefore, when such a regenerator is incorporated in a Stirling refrigerating machine, most of the working gas flows through where the gaps are relatively large, and little of it flows elsewhere, making the flow of the working gas through the regenerator 8 uneven. This makes it impossible to use the whole regenerator 8 effectively for heat storage, and thus lowers regenerated heat exchange efficiency, degrading the performance of the Stirling refrigerating machine.
The working gas sealed in the cylinder 1 sometimes contains moisture, and the moisture may freeze inside the expansion space 7 and stick to the displacer 2, causing friction between the displacer 2 and the cylinder 1 and thereby hindering smooth sliding. This, too, degrades the performance of the Stirling refrigerating machine.
The moisture may also condense inside the expansion space 7 and flow into the gaps between different layers of the film, hindering the flow of the working gas through those gaps and thereby making it impossible to use the whole regenerator 8 effectively for heat storage. This, too, degrades the performance of the Stirling refrigerating machine.
An object of the present invention is to provide a Stirling refrigerating machine in which the unevenness of the flow of the working gas passing through the regenerator has been alleviated to achieve higher regenerated heat exchange efficiency. Another object of the present invention is, in a Stirling refrigerating machine, to remove moisture contained in the working gas and thereby prevent degradation of the performance of the Stirling refrigerating machine resulting from condensation or freezing of the moisture. Still another object of the present invention is, in a Stirling refrigerating machine, to remove impurities contained in the working gas and thereby prevent clogging of the regenerator caused by the impurities.
To achieve the above objects, according to the present invention, a Stirling refrigerating machine is provided with: a piston and a displacer provided coaxially inside a single cylinder and reciprocating axially inside the cylinder with identical periods but with different phases; an expansion space formed by partitioning off one end portion of the inside of the cylinder with the displacer; a compression space formed by partitioning off a middle portion of the inside of the cylinder with the displacer and the piston; and a regenerator provided in the flow path for a working medium formed between the outside of the movement path of the displacer and the inner surface of the cylinder. Here, uniformizing means for making the flow of the working medium passing through the regenerator uniform is provided on one or both of the expansion-space and compression-space sides of the regenerator.
In this structure, the working medium reciprocating between the expansion space and the compression space passes through the flow uniformizing means immediately before flowing into the regenerator. The flow uniformizing means makes the flow of the working medium passing through the regenerator uniform.
Alternatively, moisture absorbing means for removing moisture contained in the working medium is provided on one or both of the expansion-space and compression-space sides of the regenerator.
In this structure, the working medium reciprocating between the expansion space and the compression space passes through the moisture absorbing means immediately before flowing into the regenerator. The moisture absorbing means removes moisture contained in the working medium.
Alternatively, a filter for removing impurities contained in the working medium is provided on one or both of the expansion-space and compression-space sides of the regenerator.
In this structure, the working medium reciprocating between the expansion space and the compression space passes through the filter immediately before flowing into the regenerator. The filter removes impurities contained in the working medium.
Alternatively, flow uniformizing means shared as moisture absorbing means for making the flow of the working medium passing through the regenerator uniform and for removing moisture contained in the working medium is provided on one or both of the expansion-space and compression-space sides of the regenerator.
In this structure, the working medium reciprocating between the expansion space and the compression space passes through the flow uniformizing means shared as moisture absorbing means immediately before flowing into the regenerator. The flow uniformizing means shared as moisture absorbing means makes the flow of the working medium passing through the regenerator uniform and removes moisture contained in the working medium.
Alternatively, flow uniformizing means shared as a filter for making the flow of the working medium passing through the regenerator uniform and for removing impurities contained in the working medium is provided on one or both of the expansion-space and compression-space sides of the regenerator.
In this structure, the working medium reciprocating between the expansion space and the compression space passes through the flow uniformizing means shared as a filter immediately before flowing into the regenerator. The flow uniformizing means shared as a filter makes the flow of the working medium passing through the regenerator uniform and removes impurities contained in the working medium
Alternatively, moisture absorbing means shared as a filter for removing moisture and impurities contained in the working medium is provided on one or both of the expansion-space and compression-space sides of the regenerator.
In this structure, the working medium reciprocating between the expansion space and the compression space passes through the moisture absorbing means shared as a filter immediately before flowing into the regenerator. The moisture absorbing means shared as a filter removes moisture and impurities contained in the working medium.
Alternatively, flow uniformizing means shared as moisture absorbing means and as a filter for making the flow of the working medium passing through the regenerator uniform and for removing moisture and impurities contained in the working medium is provided on one or both of expansion-space and compression-space sides of the regenerator.
In this structure, the working medium reciprocating between the expansion space and the compression space passes through the flow uniformizing means shared as moisture absorbing means and as a filter immediately before flowing into the regenerator. The flow uniformizing means shared as moisture absorbing means and as a filter makes the flow of the working medium passing through the regenerator uniform and removes moisture and impurities contained in the working medium.
The flow uniformizing means, moisture absorbing means, filter, flow uniformizing means shared as moisture absorbing means, flow uniformizing means shared as a filter, moisture absorbing means shared as a filter, or flow uniformizing means shared as moisture absorbing means and as a filter may be made of a material having an adequate heat capacity, so that they are given the ability to store a certain amount of heat.